Copper plating brightener



United States Patent COPPER PLATING BRIGHTENER Daniel R. France, Brooklyn, N. Y.

No Drawing. Application June 15, 1955, Serial No. 515,778

6 Claims. 01. 204-52 This invention relates to new and useful improvements in bright plating solutions.

More particularly, the present invention proposes to provide a brightener composition or addition which can be added to plating solutions to give the plated deposits a bright efiect so that there will be no need for polishing or recleaning or further plating.

Another object of the present invention proposes providing a method and a solution whereby any plating solution can be brought up to a basic solution and a complex mixture of three brightener additives added to provide a standard bright plating solution which can be worked at moderate or cold temperatures to produce a greatly improved brightening efiect on plated deposits.

Still another object of the present invention proposes to provide a method and a solution easy and inexpensive to use and which requires no special skills or experience to produce uniform, top grade Work.

Further objects, features and advantages of the present invention will be apparent from the following description and appended claims.

For one gallon of the brightener composition in accordance with the present invention, the following are the proportions:

This brightener is added to a basic alkaline plating solution in quantities of up to six ounces of brightener to one gallon of plating solution depending on the temperature of the plating bath to be operated.

A typical basic plating solution is as follows:

Sodium cyanide, two and one-half to four ounces,

Copper cyanide, two and three-quarters to four and one-half ounces,

Sodium hydroxide, one-half to five ounces,

Sodium and potassium bitartrate (Rochelle salts), two

and one-half to four ounces,

Water, to make one gallon.

This is the formula for the basic mixture for a bright plating solution to which the brightener is added to render the solution to plate bright. The solution can be diluted or made more concentrated as desired. The mixture when completely compounded should be heated to 165 degrees Fahrenheit and remain twenty four hours before use is made of it.

The brightener may have in place of the lead tartrate,

lead monoxide, lead phenolsulphonate or lead subacetate.

2,778,788 Patented Jan. 22, 1957 2" Likewise, in place of the cadmium oxide, cadmium cyanide may be used.

The brightener may be made up as three separate brighteners, the first brightener in one-quart proportions being:

Y Molybdic acid, four ounces,

Water, one pint,

Sodium hydroxide, suflicient to dissolve all the molybdic acid,

Water, to make one quart.

The second brightener, in one quart proportions is as follows: 1

Lead tartrate, one ounce, I Sodium hydroxide, suflicient to .dissolve all the lead tartrate,

Water, to make one quart.

The third brightener, in one quart proportions, is as follows:

Ammonium acetate, twenty grams,

Ammonium hydroxide, thirty cubic centimeters, Wetting agent, thirty cubic centimeters,-

Water, to make one quart.

The molybdic acid can be reduced to two ounces per gallon of brightener.

Bright plating solutions of proper chemical formulation and brightener additions canbe worked at a temperature 'of degrees Fahrenheit to degrees Fahrenheit. The hotter the solution, the faster it will plate, but the temperature should not run over degrees Fahrenheit. If the temperature does rise over this, the current density will have to be increased to give bright deposits in low current density areas.

A bright copper plating solution such as has been described can be prepared as follows: heat one-half the required amount of water to 130 degrees Fahrenheit. Add the following in the order specified: NaOH until dissolved; NaCN until dissolved; CuCN until dissolved; KNaC4H4O6.4I-I2O until dissolved; add brighteners one, two and three in the proportions required; add water to the desired level and heat to 165 degrees Fahrenheit.

An alternate method is as follows: NaOH until dissolved; CuCN (this will not dissolve but will go into the solution easily giving the solution a slightly orange color); KNaC4H40s.4H2O until dissolved; then add NaCN slow- Ely until all the CuCN is completely dissolved. This method is recommended because the amount of NaCN can be controlled to a minimum. Then the three brighteners are added as required.

The benefits of the new brighteners are numerous. A bright plating solution having such additives can be used for many metal parts such as electric iron shells, tubing for metal furniture, automobile trim and accessories, all of which are usually chrome plated and would require but for bright plating the following operations: grinding, compounding, dull copper plating, polishing, bright nickel plating, chrome plating and final polishing. With the bright copper plating .of the present invention there is no need to polish the copper plate, no need to reclean the surface before nickel plating, and probably eliminating the nickel plating, according to the requirements' of the job or work being plated.

To increase the power of the brightener to do more work with less brightener, the lead content can be in? creased to three or four more ounces per gallon than that specified. The more lead used, the less brightener needed to do the brightening work. Likewise, ammonium acetate neutralized with ammonium hydroxide is very beneficial in larger quantities than specified. It increases the conductance of the solution without the use of sodium hydroxide. It should be noted that the amount of sodium hydroxide should not rise over one ounce per gallon of plating solution for maximum results.

As a modification, cadmium oxide or cadmium cyanidemay be omitted from the brightener. These are used as a whitener to whiten copperin low density areas.

A final additive for a maximum effect is to add one cubic centimeter of a saturated solution of chromic acid to one gallonof. plating solution with a small additional amount of sodium cyanide (approximately one-eighth ounce to a gallon of solution). This is added after the plating solution and brightener has been mixed and 1S ready for use. It-will, however, have-beneficial effects on plating solutions without the brightener.

Having fully described my invention, I claim:

1. A copper plating solution brightener comprising the following in the following" proportions, four ounces molybdic acid, one ounce lead tartrate, five grams ammonium acetate, one hundred cubic centimeters ammonium hydroxide, two hundred centimeters wetting agent, four grams sodium stannate, four grams cadmium oxide, one half ounce sodium cyanide, one half ounce sodium chloride, eight ounces sodium hydroxide and water sufficient to make one gallon of brightener.

2. A copper plating" solution brightener comprising the following in the following proportions, four ounces of molybdic acid, one ounce of lead tartrate, five grams ammonium acetate, one hundred cubic centimeters ammonium hydroxide, two hundred cubic centimeters wetting agent, four grams sodium stannate, four grams cadmium cyanide, one half ounce sodium cyanide, one half ounce sodium chloride, eight ounces sodium hydroxide and water sufiicient to make one gallon' of brightener.

3. A copper plating solution brightener comprising the following in the following proportions, four ounces of molybdic acid, one ounce lead phenolsulphonate, five grams ammonium acetate, one hundred cubic centimeters ammonium hydroxide, two hundred cubic centimeters wetting agent, four grams sodium stannate, four grams cadmium cyanide, one half ounce sodium cyanide, one half ounce sodium chloride, eight ounces sodium hydroxide and watersufiicient to make one gallon of brightener.

4. A copper plating solution brightener comprising the following in the following proportions, four ounces of molybdic acid, one ounce lead subacetate, five grams ammonium acetate, one hundred cubic centimeters ammonium hydroxide, two hundred centimeters wetting agent, four grams sodium stannate, four grams cadmium cyanide, one half ounce sodium cyanide, one half ounce sodium chloride, eight ounces sodium hydroxide and water sufficient to make one gallon of brightener.

5. A copper plating solution brightener comprising the following in the following proportions, four ounces of molybdic acid, one ounce lead monoxide, five grams ammonium acetate, one hundred cubic centimeters ammoniumhydroxide, twohundred cubic centimeters wetting agent, four grams sodium stannate, four grams cadmium cyanide, one half ounce sodium cyanide, one half ounce sodium chloride, eight ounces sodium hydroxide and water sufiicient to make one gallon of brightener.

6. A copper plating solution brightener comprising the following in the following proportions, four ounces mo lybdic acid, one ounce lead tartrate, five gram ammonium acetate, one hundred cubic centimeters ammonium hydroxide, two hundred cubic centimeters wetting agent, four grams sodium stannate, four grams cadmium oxide, one half ounce sodium cyanide, one half ounce sodium chloride, eight ounces sodium hydroxide and water sufficient to make one gallon of brightener, and one cubic centimeter of a saturated solution of chromic acid to one gallon of solution with one-eighth of an ounce of sodium cyanide.

No references cited. 

1. A COPPER PLATING SOLUTION BRIGHTENER COMPRISING THE FOLLOWING IN THE FOLLOWING PROPORTION, FOUR OUNCES MOLYBDIC ACID, ONE OUNCE LEAD TARTRARTE, FIVE GRAMS AMMONIUM ACETATE, ONE HUNDRED CUBIC CINTIMETERS AMMONIUM HYDROXIDE, TWO HUNDRED CENTIMETERS WETTING AGENT, FOUR GRAMS SOLIUM STANNATE, FOUR GRAMS CADMIUM OXIDE, ONE HALF OUNCE SODIUM CYANIDE, ONE HALF OUNCE SODIUM CHORIDE, EIGHT OUNCES SODIUM HYDROXIDE AND WATER SUFFICIENT TO MAKE ONE GALLON OF BRIGHTENER. 